Gorgeous gardenias

Fragrant gardenias are beloved in the garden but cultivating these beautiful blooms isn’t always so easy. Helen Young shares her secrets for growing success.

Gardenias are among the most popular garden plants because of their divinely perfumed white flowers and glossy green foliage. They flower from late spring through autumn, even over winter in the right spot, and their fragrance is often associated with summer holidays and Christmas time. The flowers are also lovely to pick – even one bloom will fill a room with its scent.

They are not, however, the easiest plants to grow well. They like luxurious conditions to thrive and that means giving them the right soil, position and care so they can reward you.

WHAT THEY LIKE

Gardenias are subtropical plants, native to eastern Asia, and like mild to warm, humid climates with summer rain. Some labels claim they can grow in shade, but insufficient sun causes them to grow sparsely and spindly, and they won’t flower. They need at least four hours of sun per day to thrive. Some of the best, most prolific gardenias such as ‘Florida’, grown in full sun, can keep bearing flowers most of the year if they have plenty of soil moisture and food. The soil should be well drained, slightly acidic, and rich in organic matter. Protect their shallow roots from drying out with a mulch of compost, sugar-cane mulch or hay, and keep them well watered. A drip irrigation system is ideal. Gardenias are greedy plants, so fertilise them two or three times during the warm months with an organic-based fertiliser for acid-loving plants such as Neutrog Kahoona or Osmocote Plus Organics

Roses, Gardenias and Azaleas.

In cooler climates, gardenias need a warm microclimate, perhaps against a north-facing wall and sheltered from cold winds and frost. In summer-dry areas, they need additional summer watering and protection from the hottest westerly sun. If your soil is alkaline or sandy, grow gardenias in pots using top quality potting mix, ideally one for acid-loving plants.

To keep plants looking lush and bushy, prune in early spring before the flower buds begin to form. You can also prune just after the main flowering period.

USES

While gardenias are mostly used as small to medium shrubs in the garden, they make a beautiful informal, flowering hedge along a front fence or under a window. Grow them around outdoor entertaining areas, as the fragrance is equally as strong at night. Gardenias are also grown as standards (like a ball on a stick), which are ideal for more formal layouts, either as a pair to flank an entrance, or in pots, or as a row along a path or driveway. Prostrate varieties such as ‘Radicans’ are useful as a groundcover or edging, or to spill over the edge of a wall.

VARIETIES

The classic, and possibly the best, variety is Gardenia augusta ‘Florida’. This 1x1-metre rounded shrub bears a constant succession of waxy, double flowers over a long period, including winter when they’re in the right, sunny spot. ‘Magnifica’ is the tallest variety at 2x1.5 metres, producing extra large flowers and leaves. ‘Aimee Yoshiba’ also has larger, double white blooms but is 1.2-1.5 metres tall. Note that larger varieties tend to have shorter flowering periods. More compact than ‘Florida,’ but still with double flowers, is ‘Ocean Pearl’, which grows to a neat 50x50 centimetres.

In some varieties the white blooms age to golden yellow. ‘Golden Magic’ is one of these varieties and grows to 1.5x1 metres; ‘Professor Pucci’ is a similarly sized bush with particularly large white blooms that fade to buttery gold. Also available is ‘White Gold’, which is taller at 2x1.2 metres.

More recent releases feature simpler, single flowers. Gardenia ‘Super Star’ has masses of single, highly perfumed flowers throughout the year, peaking in spring and summer. It has narrow leaves on a 1.5-metre shrub and tolerates light frosts. ‘Grandiflora Star’ and ‘Star’ are compact bushes about 50 centimetres tall and wide, whose single, white flowers have petals that fan out in a star shape.

G. ‘Radicans’ is a prostrate growing form, reaching 50 centimetres tall and spreading over 1 metre. The flowers are small but numerous; the leaves are small and narrow. An improved cultivar ‘O So Fine’ has even finer leaves that form a dense groundcover spreading over 1 metre and reaching just 30 centimetres tall.